1. Field of the Invention
The present invention relates to an image processing apparatus connected to an IEEE 1394 serial bus, etc., and an image processing method therefor.
2. Related Background Art
Various image processing apparatuses and systems are known that transmit command statuses via a serial bus to a plurality of modules or to a plurality of apparatuses.
In addition, for the transmission of binary monochromatic image data, which have a small volume, image processing apparatuses that transmit image data and command statuses via a serial bus are well known.
Furthermore, there is a well known, commonly employed technique for outputting data to an image processing apparatus that employs a standardized interface, such as a SCSI (Small Computer System Interface) or a centronics.
However, when the data to be transmitted is color image data, which has a large volume, the conventional transmission of such data performed via a serial bus is not practical because an extended period of time is required.
This problem can be resolved to a degree by increasing the transmission speed of the serial bus. However, for an image processing apparatus, such as a copier, for which real-time image data transmission is required, the intermittent command status transmissions that occur interfere with the transmission of image data. Thus, it is difficult to employ a serial data bus, since the time by which the transmission of image data can be completed can not reliably be ascertained. As a result, a dedicated parallel bus must be used for image data transmissions.
On the other hand, since there is an increased demand for a reduction in the sizes of such products as copiers, which are generally used in offices, and a concurrent request that their functions be improved, not enough space is available inside these common office products to accommodate a dedicated parallel bus for the communication of image data.
Furthermore, the conventional image data transmission protocol for the transmission of image data via a serial bus is limited to a single protocol that is peculiar to an individual company that manufactures image processing apparatuses, so that the expansion property of the protocol is inferior.
Therefore, a technique has been proposed by which image data would be transmitted by employing an interface such as an IEEE 1394-1995 high performance serial bus (hereinafter referred to as an IEEE 1394) that can be used to connect together various types of apparatuses.
However, if with the IEEE 1394 standards an image data transmission source can not successfully perform an isochronous transmission for which a transmission time can be reliably ascertained, the transmission of the image data will fail.
In addition, if because of an inherent problem affecting the image processing apparatuses produced by a manufacturing company the IEEE 1394 standards can not provide complete coverage for those apparatuses, the protocol that tends to be employed is one that is peculiar to the specific manufacturing company.
To resolve the above shortcomings, it is one objective of the present invention to provide an image processing apparatus that can perform the steady, high speed transmission of image data via a single serial bus, even when command statuses and a large quantity of color image data must be transmitted, or even when conflicts develop among a plurality of jobs, and to provide a timing controlled operating method therefor.
It is another objective of the present invention to provide an image data transmission compensation method and system for compensating for the transmission of image data and, accordingly, for improving the reliability of an image processing apparatus.
It is an additional objective of the present invention to provide an image data transmission compensation method and system wherein, for the transmission of image data via a system bus, an inherent problem affecting the operation of an image processing apparatus can be resolved based on the protocol standards, and the expansion property can be improved.
To achieve the above objectives, according to the present invention an image processing apparatus, for which a plurality of modules are connected together via a high-speed serial bus along which at least one isochronous packet and at least one asynchronous packet, which are assigned for a predetermined number of channels, can be sequentially transmitted during a single transmission cycle, and by which image data can be transmitted to the plurality of modules by assigning to the isochronous packet the transmission to the modules of image data and by assigning to the asynchronous packet the transmission of a command status, comprises:
determination means for determining whether the number of channels available in one cycle is adequate for the execution of a job that includes the transmission of image data;
delay time prediction means for, when the determination means ascertains that the number of channels available is not adequate, predicting a delay time for the time required before the transmission of the image data included in the job is completed; and
change means for dynamically changing an operating timing for a destination module for the image data in accordance with the delay time that is predicted by the delay time prediction means.
In addition, to achieve the above objectives, an image data transmission compensation method according to the present invention, for an image processing apparatus that is connected via a common serial bus, comprises:
an image data transmission prediction step, performed at an image data transmission source before transmission of image data to the image processing apparatus and in accordance with a transmission method for ascertaining a data transmission time using the common serial bus, of predicting whether or not transmission of the image data can be performed successfully;
a prediction result transmission step of transmitting to the image processing apparatus the results obtained at the image data transmission prediction step; and
a reception method change step of changing an image data reception method based on the results received by the image processing apparatus.
Furthermore, to achieve the above objectives, an image data transmission compensation method according to the present invention, for an image processing apparatus connected via a common serial bus, comprises:
a first protocol execution step of executing the initial protocol that is not related to the protocol type of the image processing apparatus; and
a second protocol execution step, following the execution of the initial protocol, of executing a protocol inherent to a plurality of image processing apparatus types.